A commonly encountered defense mechanism by which an organism protects itself against a foreign body is the formation of a capsule enclosing and isolating the foreign material. Capsule formation, while desirable with respect to the organism as a general proposition, is disadvantageous when a prosthesis is deliberately implanted and the desired result is the integration of the implant into the surrounding tissue. Perhaps the best known instance of such implants is in breast enhancement and in tissue reconstruction employing silicone rubber implants.
The scenario which gives rise to the problem this invention is designed to solve is, briefly, as follows: The implanted silicone is rapidly encapsulated by a fiber structure, composed primarily of collagen and glycosaminoglycans, and containing fibroblasts and histiocytes. The capsule then contracts, resulting in hardening and spherical deformation of the implant itself, as well as of the surrounding tissues. The implant then becomes painful, aesthetically unacceptable, and, if untreated, can result in erosion of the overlying tissues and extrusion of the implant.
The success of mammoplasty and post-mastectomy reconstruction, as well as of other procedures involving implants of soft tissue prostheses, would be greatly enhanced by use of a prosthesis which does not elicit encapsulation, or which is resistant to capsule contraction. The present invention provides soft tissue implants which resist encapsulation and subsequent contracture.